Process for the manufacture of bulky fibrous wadding materials



Aug. 31, 1965 KAZUO KAWAMURA 3,

PROCESS FOR THE MANUFACTURE OF BULKY FIBROUS WADDING MATERIALS Filed Aug. 29, 1962 DRYER DRYER TO BALER STRETCHING ACETYLATOR SPINNING United States Patent 0 3,204,017 PROCESS FDR THE MANUFACTURE OF BULKY FEBROUS WADDING MATERIALS Kazuo Kawamura, Gifn, Japan, assignor to T0510 Rayon Kabushilti Kaisha, Tokyo, Japan, a corporation of Japan Filed Aug. 29, 1962, Ser. No. 220,151 Claims priority, application Japan, June 19, 1962, 37/24,708 1 Claim. (Cl. 264-51) 3,204,017 Patented Aug. 31, 1965 Hollow rayon staples of this type are obtainable from viscose combined with a slight sodium carbonate and the cells in these fibers are highly stable to external compression.

The rayon staple fiber of the hollow crimped type referred to above can be converted into a hollow crimped acetate fiber of 45 to 50 percent acetyl contents through acetylating the fiber by bringing same in contact with high temperature acetic anhydride vapor for 40 to 50 minutes, after impregnating it with an appropriate catalyst, for instance, acetate (sodium acetate; potassium acetate) or an aqueous solution of water soluble salt such as zinc chloride and then squeezing and dehydrating in a dryer.

The crimp of the resulting hollow crimped acetate fiber is originally formed in the viscose rayon fiber while being spun, so it is a substantial crimp due to the double various other processes, such as a mechanical crimping method, or a random looping method for fibers due to air jets.

It is an object of the present invention to provide novel, improved method for the manufacture of hollow crimped acetate fibers having high bulkiness and excellent mechanical properties as wadding materials for articles such as bed underlayers, cushions, pillows, quilts and quilted clothings.

Another object of this invention is to provide novel, improved method for the manufacture of fibrous wadding materials having various excellent properties, whereby the above mentioned articles have correspondingly improved propeities such as specific gravity, and resistance to washing and feeling.

A further object of the present invention is to provide an improved method for the manufacture of fibrous wadding materials for final objective goods, at a low manufacturing cost.

Details of the manufacturing process of this invention for accomplishing the above mentioned objects and that of particular properties, features, functions, effects and advantages of products will be made clear in the following description taken in connection with the accompanying drawing which is a schematic diagram of a process embodying this invention.

When fibrous wadding materials are used for articles such as bed underlayers, cushions, pillows, quilts and quilted clothings, etc., the most important matter common to all is a sunlight-restoring property, that is, a property that even if the bulkiness of those products may decrease more or less during their use, the lost bulkiness may be restored to the original bulkiness rapidly by exposing to the sunlight.

The fact that cotton, which is easy to lose its bulkiness during use, has good sunlight-restoring property has come to my notice. Thus, the product according to this invention has been arrived at by further processing a hollow crimped rayon staple fiber which has cotton like hollow structures as well as structures similar to the special spiral structures as observed in cotton.

In general, hollow crimped rayon staple fibers produced from viscose are classified in several types with respect to their internal fiber structures, such as an independent cell type, successive cell type and a macaroni cell type. All such type may be used as starting materials for accomplishing the present purpose.

In particular, hollow crimped rayon staple fibers of continuous cell type have been selected as starting fibers for manufacturing fibrous wadding materials to fully display properties appropriate for their uses.

layer structure of the fiber per se and is a strong, excellent grade spiral crimp.

The structural crimp thus obtained is fixed by acetylating and is given further strength in resilience, which serves to impart bulkiness to the fiber.

Furthermore, the second elfect that makes this fiber appropriate for wadding purpose resides in the fact that cells are contained in the interior of fibers.

Such hollow crimped rayon staple fibers contain numerous cells in the interior of fibers while being spun from viscose, so, when acetylated, the fibers have a lower apparent specific gravity by approximately 10 percent as compared with that of ordinary crimped rayon staple fibers having been acetylated. This is also advantageous for obtaining appropriate bulkiness, and in addition, a soft touch is obtainable by introducing cells resulting in a soft resilient property. An improved thermal-insulation property can be anticipated due to the inclusion of cells.

Introduction of cells in the inside of fibers may readily be effected by the wet spinning process of viscose, and as a result, the production of raw fibers may be attained at low cost with industrial advantages.

Hollow crimped rayon staple fibers per se are not suit able for fibrous wadding materials because of their inferior resiliency and high specific gravity. For this reason, the fibers are acetylated in the fiber state to form hollow crimped acetate fibers. By thus lowering the specific gravity and simultaneously enhancing the elasticity, the above-mentioned properties are obtainable, which are appropriate to comply with the purposes referred to above, namely the bulkiness, sunlight-restoring and thermal insulation properties and pleasant touch. Thus, the product of this invention is assured of the characteristics desirable for successful marketing.

Another advantage of the present invention lies in the fact that hollow crimped acetate staple fibers obtained by acetylating hollow crimped rayon staple fibers show a low water content, approximately 5% water, which is not too high nor too low, to affect the above-mentioned appropriate properties complying with the object of this invention, but imparting rather optimum conditions. Moreover, even when washing becomes necessary during use, the drying velocity after washing may be rather high but it does not happen that the water content is reduced too low to attain comfortable wear and feeling properties, thereby accomplishing effectively the above-mentioned objects.

The products made according to the present invention possess excellent properties for wadding purposes and in addition they also can advantageously be used as an excellent starting fibrous material to obtain soft, bulky and graceful nonwoven fabrics by utilizing such properties.

For further clarifying the product of this invention, the manufacturing process and properties of the products obtained will be explained by way of example in the following:

EXAMPLE A viscose having a polymerization degree 300 of cellulose, an aging degree in Hottenroth value and a viscosity of 70 poises, which was manufactured by mixing 1.8% sodium carbonate with ordinary viscose containing 8% cellulose and 6% total alkali, was spun at spinning speed of 50 meters per minute through nozzles, each having 3000 holes with an 0.08 mm. diameter of each hole, in a spinning bath held at 52 C. comprising 410 gm./liter Na SO gm./ liter Zn S0,, and 100 gm./ liter H 80 and 'then passed through second and third hot water baths,

when 65% stretching was imparted in the second hot water bath.

As is illustrated on the drawing, the resulting stretched product was cut and scoured to form hollow crimped rayon staple fibers which, in a catalyzer application step, were impregnated with 20% aqueous solution of sodium acetate at C. for 10 minutes and dehydrated under compression to a weight ratio of 2.0 times the original dry weight of starting fibers. Then, after the contained water had been removed in a dryer, the fibers were acetylated in the fiber state by bringing them in contact with acetic anhydride vapor of 135 C. for 50 minutes; after being washed in water and dried to obtain hollow crimped acetate fibers having 50% acetyl contents, the fibers were ready for baling.

Testing method Web-formed fibers are piled up to form 30 cm. squares and make a mat in total weight of 200 gm. Then two such mats are piled on top of each other and are then compressed with a load of 10 gm. per cm for 8 hours, and then 4i unloaded in the subsequent 16 hours. The height of the mat is measured after the above-mentioned operation has been repeated for ten times. The thus obtained value A compared with the initial height B of the mat to obtain a fatigue degree from the expression What we claim:

A process for the manufacture of bulky, low specific gravity and high resilient wadding material of hollow, structurally crimped rayon staple fibers comprising the steps of (a) mixing 1 to 3% sodium carbonate with conventionally manufactured viscose,

(b) spinning the mixture in a spinning bath solution consisting of a conventional concentration of Na SO ZnSO and H to effect crimping and foaming of the mixture,

(c) stretching the crimped and foamed product in a hot water bath,

(d) cutting and souring the stretched product to form hollow and crimped rayon staple fibers,

(e) impregnating said staple fibers in an aqueous solution of salt selected from the group consisting of sodium acetate and zinc chloride at a temperature of 30 for a period of ten minutes, and

(f) drying and acetylating the impregnated staple fibers in an acetic anhydride vapor for a period of fifty minutes.

References Cited by the Examiner UNITED STATES PATENTS 1,427,330 8/22 Rousset 18-54 1,831,030 11/31 Picard 1854 2,136,464 11/38 Picard et al. 264-54 2,476,293 7/49 Hall et al. 18-54 2,492,425 12/49 Hall et al. 2 64-54 2,768,870 10/56 Drisch et al. 264200 2,780,511 2/57 Takagi 8121 2,780,512 2/57 Inoshita 18--54 2,834,093 5/58 Woodell 161169 2,835,551 5/58 Kosuge 1854 3,057,037 10/62 Carney et al. 161169 3,084,021 4/63 Morimoto 264- ALEXANDER H. BRODMERKEL, Primary Examiner.

WILLIAM STEPHENSON, Examiner. 

